The former Rotherham centre-back was taken off with a hip injury in Tuesday's goalless draw with Exeter and will not be available to face the Dons.
The U's are already without defender Jake Wright, who is sidelined for up to six weeks with a knee injury.
Lewis will also check on veteran forward Dave Kitson, who has been on the sidelines with an ankle injury.
- Sports & Recreation
- Disease & Medical Conditions
- Jake Wright